The actress, 45, meandered around the streets of L.A. in a frumpy outfit comprised of gray sweatpants, a loose-fitting henley, and baggy sweater. Justin Theroux's fiancee once again swapped her sunny blonde tresses for a darker shaggy hairstyle. With barely a smudge of makeup on her face, Aniston made multiple weary expressions as she acted out her role as Claire Simmons.

The premise of the indie flick (also executive produced by Aniston) is centered on Claire, a grieving mother who becomes fixated with a woman in her chronic pain support group. The woman (Anna Kendrick) later commits suicide, leaving behind a grieving husband (Sam Worthington) and pushing Aniston's character into a place where she has to openly confront her personal issues.

While Aniston and Worthington's characters eventually develop a relationship, real-life beau Theroux has been stopping by the set to support his fiancee. He recently "roared up on his motorcycle" and headed "straight into her trailer," an eyewitness told Us Weekly. According to the insider, the engaged couple "timed it perfectly," between shooting and relaxation on set.

Cake also stars The Mindy Project's Chris Messina. Tell Us: What do you think of Jen's natural look?